The Increase of Radiative Lifetime of Free Excitons in Selectively Si-doped GaAs/AlxGa1-xAs Heterostructures

The time resolved photoluminescence spectra of selectively Si-doped GaAs/Al x Ga 1- x As heterostructures have been investigated over a wide temperature range from 3.6 K to 300 K in order to identify possible mechanisms behind the observed increase in radiative lifetime of free excitons. Possible mechanisms of carrier recombination are discussed with emphasis on the unique traits of excitonic photoluminescence. The intensive lines found in the spectra of the heterostructures are associated with the formation and enhancement of free exciton emission in the flat band region of an active i -GaAs layer. We have established that the free exciton radiative lifetime in the heterostructures increases about two times, up to 1.44 ns in comparison with lifetime 0.6 ns of i -GaAs layer without a heterostructure for first sample and up to 0.92 ns from 0.4 ns for second sample at 3.6 K temperature. DOI: http://dx.doi.org/10.5755/j01.ms.20.2.6329